Currently in the Rebreather market, a lot is being said about equipment such as the JJ-CCR, the rEvo, the Prism2, the SF2, the Megalodon CCR, the Pathfinder CCR and the Inspiration XPD (also better known as Inspiration Vision). All these Rebreathers have something in common. They are eCCR's, which means electronic closed circuit rebreathers. And all have a bus system, which is installed into the electronic system. Since there are many myths and half-truths, I want to use this contribution to shed some light onto the darkness of bus technology.

If you search in Wikipedia what Bus systems are you will find the following definition:

In computer architecture, a bus is a communication system that transfers data between components inside a computer, or between computers. This expression covers all related hardware components (wire, optical fiber, etc.) and software, including communication protocols.

As already announced in part 1 of this article, we now illuminate the different bus types. As a reminder, it was the I2C Bus, the ISCANTM and the DiveCAN® installed in rebreathers.

The I2C bus are in Seabear products and AP Diving Rebreathers, i.e. the Inspiration XPD, the Inspiration EVP (formerly known as Evolution+) and the Inspiration EVO (also known as Evolution).The rebreathers from Innerspace System Corp., the Megalodon CCR and the Pathfinder CCR use the ISCANTMThe DiveCAN® is installed in all rebreathers that use Shearwater electronics. These are for example the JJ-CCR, the rEvo, the Hollis Prism2, the SF2 and the O2ptima. The newest member in these family is the XCCR.

I2C Bus

Let’s consider first the I2C bus because this is the one that has been used longest in rebreathers. When pronounced, I2C means Inter-Integrated Circuit.